Method of manufacturing mineral wool product



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METHOD F MANUFACTUBIN WOOL PRODUCT s PATENT OFFICE GHINERAL narnia T. con, wuusm M. Memphis, ina nerachel V. Swindell, Somerville, N. J., aligner:

to Johns-Yanvlile Corporation, New York, N. Y., a corporation of New York Appumioamy 29, 1940, serial No. 337,178 1o claims.' v(o1. 154-428) The present invention is directed to a dry -process for the manufacture of mineral wool thermal insulating products of relatively high density -and having the desirable properties of insulating materials sold under the registered trademark "Rock Cor and is a companion case to application Serial No. 336,896, filed May 24, 1940, in the names of Harold T. Coss, William M. MacAlpine, and Louis A. Hawthorne. It will -be understood that the term mineral wool is employed herein in a generic sense to denote fibres formed from rock, slag. glass, and other conventional raw materials and mixtures thereof.

As has been pointed out in said companion application, the prior known method of manufacturing Rock Cork has been relatively slow and expensive due to the multiplicity of operations involved. Also, certain of these operations have resulted in the mashing or breaking of the fibres, increasing the density and weight of the lproduct to an undesirable extent and decreasing its insulating eiiiciency; the heterogeneous arrangement of the fibres has reduced the insulating properties of the product; the necessity of molding the product has resulted in a surface crust which must be removed. with the resultant loss of material; and the large amount of organic material in the binder has reduced the resistance of the product to combustion.

The instant invention has, as an object, the provision of a method for the manufacture of a product having the desirable characteristics of the present Rock Cork but which overcomes the above-noted disadvantages and in which the operation is continuous from the formationv of the fibres to the final packing of the product. More particularly, the instant invention has for an object the provision of such method in which a continuous felt of mineral wool fibres containinga binder disseminated therethrough is subjected to a treatment to compress the felt at and adjacent the surfaces and to set or harden the binder at such locations to form surface layers highly resistant to deformation, and thereafter to a treatment to set the binder in the interior of the felt while the felt is held compressed to a desired thickness. 1

carrying out the method of the invention. Conventional portions of the apparatus are not shown in detail as they may take different forms. The apparatus generally comprises a melting furnace I0, which may be a cupola, tank furnace. or y the like, of any conventional design. Molten slag. rock, or mixtures thereof, or otherl conventional raw materials melted in furnace Il, issues therefrom in the form of a stream through orifice l2 and falls into the path of a steam jet I4, which shreds it into a great multiplicity of extremely iine fibres which are carried by the force of the steam jet and in gaseous suspension into blow chamber i6.

A binder is forced into the suspension of the fibres -by any of the known conventional means for this purpose. Preferably, an atomizing binder jet of a known type. as diagrammatically illustrated at I8, is used. The binder is added in proportions of, say, between to 30% of the weight of the bres, preferably between 18 and 24%. The mineral wool fibres and the minute binder particles settle in the blow chamber, the Ibinder particles collecting on the fibres.

Binders suitable -for use in the instant inven- .tion are preferably those referred to in said comy panion application, wherein the different binder requirements are set out in detail. Brieiiy stated, it may be said that the binders which,

have been found most successful are those comprising:

Our invention will be more fully understood and further objects and advantages thereof will become apparent when reference is made to the more detailed description thereof which is to follow and to the accompanying drawing, in which:

Fig. 1 is a diagrammatic elevational view of a portion of an apparatus employed in the method of the instant invention, and

Fig. 1a is a continuation of the apparatus disclosed in Fig. 1.

Referring now to the drawing, there is dia` grammatieally shown an apparatus suitable for Voo bery asphalt having a melt point of 21o-220 (l) A hard pressure still residue toughened with a softer, blown or refined asphalt, or petroleum tailings. A typical formula is:

Per cent Insulating asphalt 33.2 Rock Cork asphalt 33.2 H. P. asphalt 26.6 Chlorinated oompound..... 7.0

(2) Gilsonite fluidied with a pressure still residue asphalt, a specific example being:

(3) Thermoplastic resin, for example:

Per cent Rosin 90.0 Chlorinated compound 10.0

F. and a penetration of 5-9 at 77 F. Gilsonite is a natural asphalt having amelt point of T-325 F. and 0 penetration at '77 F. The` chlorinated compound is a chlorinated aromatic or cyclic hydrocarbon with a minimum chlorine content of 45% and is inclined as a fireproofing ingredient. The penetrations and melt points referred to are those determined by standard A. S. T. M. tests. The rosin may be gum or wood rosin, limed rosin, an ester gum, or the hk''he blow chamber I6, which receives the suspension of fibres and binder, has a bottom wall comprising a continuously moving endless belt or conveyor traveling in the direction indicated by the arrow, on which the fibres settle in felted relationship with the binder particles disseminated substantially uniformly throughout the felt. Suitably, the belt may be of a foraminous nature and a suction device provided therebelow as diagrammatically indicated at 22 to aid in securing uniform density of fibre deposit throughout the width of the blow chamber.

The felted mass of fibres is carried from the blow chamber b y conveyor 20 and preferably compacted to a slight extent to form a relatively thick blanket 23 by press roll 24 located at the exit end of the blow chamber. rate of movement of conveyor 20 is correlated to the rate of deposition of the fibres to insure uniformity in density of the product as by means of a weighing scale 29 over which the felt passes. Weighing scale 28 is operatively connected to the drive of conveyor 20 by any suitable means (not shown) whereby increase lin the weight of the blanket increases the speed of movement of the conveyor and vice versa.

The felted `blanket with the binder disseminated therethrough is heated to a temperature sufficient to plasticize the binder. This may be accomplished by an oven 34 including foraminous conveyor belts 28 which carry the felt through the oven, the belts being driven by suitable pulleys 30 in the direction indicated by the arrows. The upper conveyor belt is suitably made vertically adjustable as by means of the mechanism diagrammatically illustrated at 32 and in the operation of the device the belts are so spaced that the blanket is only slightly compressed as it passes therebetween. Air at a temperature, say, between 200-300 F., depending upon the melting point of the particular binder employed, is circulated from any suitable air heating means, such as furnace 35, through ducts 36 opening into the oven below the upper reach of the lower conveyor 28, the heated air being forced through the conveyors and the blanket held therebetween.

Preferably, the,

around drums 42 and 44. "\The adjacent reaches of the belts are supported to prevent yielding by beams or other supports 4I. The upper belt is arranged for adjustment relative to the lower' belt by a raising and 'lowering device 46. The belts, in this instance, preferably comprise thin steel bands continuous the width of the blanket. Within drums 42, supporting the forward ends of the belts, are provided a plurality of heating means 48, such as gas jets, lamps, or the like, whereby the belts are heated above the melting point of the binder. The gap between belts 4G is adjusted to compress the blanket to substantially less than its desired finished thickness.

Located between the drums 42 and 44 are a plurality of cold water sprays 66 or other cooling means which serve to quickly chill the belts and, in turn, solidify the binder adjacent the surfaces of the blanket. The blanket passes from between the belts to a second set of belts 50, supported for travel in the directions indicated by the arrows, on drums 52.

The upper belt 50, similarly as in the case of the upper belts of the devices previously described, is mounted to be raised and lowered relatively to the lower belt, the gap between the adjacent reaches of the belt being adjusted so as to compress the blanket to its final desired thickness. Also, the adjacent reaches of both belts are supported to prevent yielding of the same under the pressing action as by means 55. Belts vmay be steel bands, similarly to belts 40, or may be of any other suitable type. Located between the drums 52 are a plurality of cold water Alternatively, the plasticizing of the binder may take place in the blow chamber I6. Depending upon the particular type of blow chamber employed, th'e residual heat in the fibres may be sufficient for this purpose, or if this is not the case, the temperature of the blanket may be raised to that necessary as by providing heating units or introducing heated air into the blow chamber.

In accordance with our present invention, the blanket passes from the oven 34 or directly from the blow chamber, if the binder is plasticized therein, to a device for compressing and densifying the blanket at the surfaces thereof and for hardening the binder in the condensed surface portions. In its preferred form, this device comprises endless belts 40, ,suitably mounted for travel in the directions indicated by the arrows minute.

The blanket, after leaving the belts 50, passes` through any suitable cutting and trimming de- A vices where it is subdivided into blocks or sheets of the desired size and is ready for packing and shipment.

In the operation of the method for the production of materials, say, of 2" finished thickness, a felted blanket, which may be, say, 12" in thickness as it leaves the blow chamber and containing a binder of any of the types previously referred to in a proportion between 10 and 30% of the weight of the fibres, is warmed to a temperature, say, of 220-250 F. in oven 34 or in the blow chamber I 6 to soften or plasticize the binder. The blanket then passes between heated belts 40 where it is compressed to a thickness of, say, 11/2 and then immediately surface chilled by the application of the cold water from sprays 43. It has been determined that the belts 40 should be of such length and driven at such speed that chilling takes place for approximately one The hot belts, during the compression of the felt, serve to convert the binder at and adjacent the felt surfaces to a highly plastic state, whereby a greater condensing of the blanket occurs at the surfaces than in the interior. The chilling of the surfaces hardens the binder in these portions whereby they retaintheir condensed state.

The felt, after leaving the belts 40, expands in thickness due to the resiliency of the felted structure and the still plastic state 'of the binder in its interior, and passes between belts 50 where andere aus, mdcoonnstnsfeltwnue maintained at' through the action of the cold water sprays Il to harden or set the binder in the interior of the felt, and preferably, the felt is completely cooled.

The product made as described above has the fibres lying in a plane substantially parallel to the major surfaces whereby the product exhibits 'increased insulating emciency as compared to a product in which the fibres are in a heterogeneous arrangement. Also, the modulus of rupture is much higher. The heatingofthe surface of the blankets between the hot belts 40 and immediate chilling provides the blanket with hard, high density, distortion resisting surfaces, and with a porous interior of substantially less but uniform density.

Having thus described our invention in rather full detail, it will be understood thatthese details need not be strictly adhered to, but that various changes and modifications will suggest themselves to one slfilled in the art, all falling within the scope of the invention as defined by the subjoined claims.

What we claim is:

1. The method comprising forming a suspension of mineral wool fibres and a thermoplastic binder,` depositing said bres to form a felt of substantially uniform density with the binder' l,disseminated therethrough, heating the felt to soften the binder throughout the felt, compressing the felt to a thickness substantially less than the finished thickness while applying heat thereto, hardening the binder in the surface portions of the felt while the felt is under compression, freeing the felt for expansion to a desired nished thickness, and hardening the binder throughout said nnished thickness.

5. The method. comprising forming a felt from anair suspension of mineral wool fibres ands.'

thermoplastic binder with the binder disseminated throughout the felt and in a proportion of the order of 10 to 30% by weight of the fibres, slightly compressing the felt, heating the felt to soften the binder, compressing the felt to a thickness substantially less than the desired finished thickness while applying surface heat thereto, chilling the surfaces of the felt while the felt is maintained at said thickness, freeing the felt for expansion to the desired finished thickness, and cooling the felt while maintained at said finished thickness.

6. The method for the manufacture of felted mineral wool products comprising forming an air suspension of newly formed mineral wool fibres and a thermoplastic binder with the binder present in a proportion of the order of 10 to 30% by weight of the fibres, felting said fibres in a blow chamber with the binder substantially uniformly disseminated throughout the felt, heating the felt in the blow chamber'to soften the binderr compressing the felt between heated members: to a thickness substantially less than the desired finished thickness, chilling the surfaces of the felt while the felt is maintained at said thickness, freeing the felt for expansion to the desired nished thickness, and cooling the felt while mainf-tained at said finished thickness.

7. The method including forming a suspension:

while maintaining the felt at said finished thickness. v

2. The method comprising forming a suspension of mineral wool ilbres anda thermoplastic binder with the binderdisseminated throughout the felt and in a proprtion of the order of 10 lto by weight of the bres, plasticizing the binder, compressing the felt to a thickness substantially less than the desired finished thickness, cooling the surfaces of the felt while the same is under compression, freeing the felt for expansion to the desired finished thickness, and cooling the felt throughout while maintaining the same at said finished thickness.

3. The method comprising forming a suspension of mineral wool fibres and a thermoplastic binder, depositing said fibres to form a felt of substantially uniform density with the binder disseminated throughout the felt and in a proportion of the order of 10 to 30% by weight of the fibres, heating the felt to soften the binder, compressing the felt to a thickness substantially less than the desired finished thickness while applyingsurface heat thereto, cooling the surfaces of the felt while compressed to said thickness, freeing the felt for expansion to the desired finished thickness, and further cooling the felt while maintained at said finished thickness.

4. The method comprising forming a felt from an air suspension of mineral wool bres and a i while said binder is plastic to a thickness substantially less than the desired finished thickness, chilling the surfaces of the felt while the felt is maintained at said' thickness, freeing the felt for expansion to the desired nished thickcomprising bitumen and a fireprooiing ingredient. with the binder present in a proportion of the order of 10 to 30% by weightlfof the bres, dem positing said fibres to form a felt of ,substantially uniform density with the binder disseminated therethrough, compressing the felt to a thickness substantially less than the desired finished thickness while applying surface heat thereto, surface chilling the felt while the felt is maintained at comprising a hard pressure still petroleum resi-- due, a softer,bituminous material, and a fireproong ingredient, with the binder present im a proportion of the order of 10 to 30% by eight'.A of the fibres, depositing said fibres to form a felt. of lsubstantially uniform density with the binder' disseminated therethrough, compressing the felt to a thickness substantially less than the desired finished thickness while,v applying surface heat thereto, surface chilling the felt while the felt is maintained at said thickness, freeing the felt for expansion to the desired finished thickness, and cooling the'felt while maintaining the felt at said nished thickness.

9. The method including forming a suspension of mineral wool fibres and a binder, said binder comprising gilsonite iluidied with a pressure still residue asphalt and a reproong ingredient with -the binder present in a proportion of the order of 10 to 30% by weight of the fibres, de-

said thickness, freelngthe felt for expansion to the desired finished thickness, and cooling the felt while maintaining the felt at said finished thickness.

10. The method comprising forming a felt from an air suspension of mineral wool fibres and a binder, said binder comprising a thermoplastic resin and a. ireproo'ng ingredient with the binder present in a proportion of the order of 10 t'o 30% by weight of the bres, depositing said bres to form a felt of. substantially uniform density with the binder disseminated therethrough, com# pressing the felt to a thickness substantially less V than the desired finished thicknessvwhileapplylng surface heat thereto, surface chilling the felt while the felt is maintained at said thickness, freeing the felt for expansion to the desired iinished thickness, and cooling the felt while maintaining the telt at said nlshed thickness.

HAROLD T. COSS. U WILLIAM M. MACALPINE. HERSCHEL V. SWINDELL. 

